const {Readable}=require('stream')
class MyReadable extends Readable{
  constructor(){
    super()
      this.#c=='a'.charCodeAt(0);
  }
  _read(){
    this.push(String.fromCharCode(this.#c++));
    if(this.#c>'z'.charCodeAt(0)) this.push(null);

  }
  #c;



}
const mr=new MyReadable()
mr.pipe(process.stdout)